The present invention relates to a method for forming a stabilized aqueous dispersion of inorganic and/or organic particles for food stuffs. More particularly, the invention relates to a method for forming a stabilized aqueous dispersion which is useful for reducing viscosity of aqueous dispersions wherein various water-insoluble or sparingly soluble inorganic and/or organic particles for food stuffs are suspended, accelerating suspension and dispersion of the various particles, and preventing sedimentation of the suspended particles.
2. Description of the Prior Art
Aqueous dispersions wherein various organic and/or inorganic particles are suspended in aqueous medium are used for various purposes. The organic and/or inorganic particles, the subjects to be dispersed, are, for example, those organic particles for food stuffs, such as cocoa powder, fruit pulp, solid matters of miso (bean paste), solid matters of soup, etc., as well as those inorganic particles such as calcium carbonate, sachin white, talc, red oxide, magnesium hydroxide, zinc white, barium sulfate, kaolin, clay, etc. As actual embodiments of the aqueous dispersions, there can be mentioned paint & varnish; fillers; neutralizing agents for desulfurization of exhausted smoke; material dispersions for ceramics; various food stuffs such as juice, chocolate milk, chocolate syrup, cocoa, miso soup, soup, zenzai (thick red bean-meal soup with sugar), shiruko (red-bean soup with sugar), etc; cosmetics such as pigment-containing foundation, milky lotion, etc.; pharmaceutical medicines such as emulsion, suspension, contrast medium, etc.; quasi-drug such as toothpaste, etc.; and the like.
Such various aqueous dispersions may be in the form of a liquid or slurry, depending on the property and amount of the suspended particles. When the particle-concentration is high, the aqueous dispersion becomes, in many cases, a slurry having a high viscosity, which is difficult to handle on use, transportation, storage, etc. Further, in some cases, the state of suspension of the particles is unstable and the particles gradually precipitate and finally separate.
Therefore, with the purpose of reducing the viscosity of the aqueous dispersions in slurry state and maintaining stability of the suspension of particles, a method of adding polyphosphates, polymers or copolymers of acrylic or methacrylic acid series, or their salts to such dispersions has been hitherto effected, and these additives are in general called a particle-dispersing agent. It has also been proposed recently to use maleic acid (or fumaric acid)/acrylic acid (or methacrylic acid) copolymers and acrylic acid (or methacrylic acid) copolymers, as a particle-dispersing agent for inorganic pigments dispersions (Japanese Unexamined Patent Publication No. Sho 61-81464).
On the other hand, in the field of food stuffs, miso soup, shiruko, zenzai, cocoa, soup, etc., are frequently sold in the form of dry powder, i.e., the so-called instant food stuffs, because of the preservability and the easiness of handling. However, there has been a problem of dispersibility of the powder or the contents in these food stuffs. For example, by merely pouring hot water into an instant miso soup, it was found that the suspended miso particles precipitated within a shorter time compared to using raw miso. Also with respect to other instant food stuffs, it was difficult to disperse the contents with water or chilled water within a short time.
Various beverages and dairy products such as milk are often commercially available in the form of mixture with a calcium compound for enriching calcium component, such as calcium carbonate, calcium pantothenate, calcium acetate or the like. However, when such products are stocked for a long time, a calcium precipitate occurs and hence deteriorates rates the qualities of the products as commercial goods.
To remove such a problem or difficulty, it has been proposed to add sucrose/fatty acid esters, sorbitan/fatty acid esters, or the like to instant food stuffs (Japanese Patent Publications No. Sho 46-28157 and No. Sho 45-29423, Japanese Unexamined Patent Application No. Sho 53-66473, etc.).
Also in the field of agricultural chemicals, there has been an inconvenience that, when the active ingredient was a solid sparingly soluble in water, the flowable preparation (aqueous suspension) prepared caused aggregation and/or separation of the active ingredient particles or, when such preparation or a wettable preparation was diluted with water, the active ingredient particles and the carrier precipitated. Therefore, nonionic, anionic, cationic or other surface active agents and viscosity-increasing agents such as CMC (carboxymethylcellulose), PVA (polyvinylalcohol), etc., have been hitherto used.
Particle-dispersing agents comprising, for example, the above-mentioned polymers of polyphosphoric acid series, polyacrylic acid series or other series or the widely used surface active agents cannot be said completely harmless against human bodies, animals and plants, and accordingly there is a limitation in their application to aqueous dispersions used for food stuffs, cosmetics, agricultural chemicals and pharmaceutical medicines. On the other hand, the above-mentioned sucrose/fatty acid esters, etc., have been used as a dispersing agent for not only food stuffs but also cosmetics, pharmaceutical medicines, etc. However, there has been a problem that their particle-dispersing effect was insufficient and, in addition, they were economically disadvantageous.
The purpose of the present invention resides in providing a particle-dispersing agent which is quite safe and harmless, even when it is taken in the human body, which does not cause any environmental pollution or any damage on plants because of its good susceptibility for biolysis, even when it discharged into a river or the like, and which has yet an excellent particle-dispersing effect.
Various reports have been hitherto made as to the properties of grain partial degradation products, especially of hydrolyzates by acid or enzyme. However, any description of their particle-dispersing action is not given in the reports, as far as we know. For example, it is described in Japanese Unexamined Patent Publication No. Sho 50-95443 that the sightly acidic gluten powder obtained by acidifying wheat gluten under a pH of 2.0-6.0 is superior as an additive for food materials, compared with one obtained by treatment with a reducing agent. In this Publication, however, any concrete effect as to the additive is not disclosed at all. Further, in Japanese Unexamined Patent Publication No. Sho-60-237939, partially hydrolysed wheat gluten obtained by hydrolysis of wheat gluten with enzyme is disclosed, and there is set forth a disclosure to the effect that the partially hydrolysed wheat gluten can be used as a substitute for caseinates in the production of imitations of cheese. However, any disclosure is not given in this Publication, as to particle-dispersing agents.
U.S. Pat. No. 2,582,965 (Coffman et al) discloses that a decomposition product of wheat gluten hydrolyzed with quick lime is more effective as a protective colloid agent for polymer emulsion compared to casein, but does not disclose that such decomposition product is effective as a particle-dispersing agent for food stuffs, however, has never been disclosed.